This is a revised small grant application to study mucosal Langerhans cells (LC) in the oral mucosa of HIV-infected subjects. The studies proposed in this application are aimed at demonstrating the feasibility of the applicant's approaches to study HIV infection and HIV gene expression in oral mucosal LC of patients infected with HIV. The aims are to assess LC morphology and numbers in oral mucosa of HIV-infected patients and to determine expression of HIV p17 in these cells, as well as to demonstrate HIV tat and rev expression patterns in these cells and their associations with oral mucosal lesions. These studies will be the basis for what is hoped to be a long-term project to study HIV gene expression patterns in LC of the oral cavity in HIV-infected patients.